Lesions within the bone can result from osteoporosis, tumor, or other pathogenic causes. Most common among the elderly population is the degenerative effect of osteoporosis, particularly the female elderly. Osteoporosis is mediated at least in part by genetic defects and a fall in circulating estrogen levels. Although calcium replacement therapy can have some beneficial effects, the larger doses of calcium involved have other less helpful consequences and accordingly, the prognosis for those with bone demineralization is not particularly good. Of great concern is the fact that every year in the United States there occurs approximately 1.2 million bone failures due to osteoporosis. Vertebral compression failures are a major orthopedic health concern of the elderly due to the long term debilitating nature of the injury.
Historically, osteoporotic vertebral body compression failures have been treated with bed rest, analgesics, and intravenous hydration during the first week after onset of the problem. These steps are followed by the prescription of a soft or firm spinal corset, depending upon the physician's preference. In most cases the corset is not worn because the patient suffers much discomfort and oftentimes greater discomfort than that due to the failure of the vertebral body. In any case, this conventional approach required extensive hospitalization and bed rest, which often results in very limited success, chronic pain, and further osteoporosis with worsening conditions of the vertebral body. The costs associated with such extended hospitalization and the negative effect on the general health of the patient from such prolonged inactivity should be avoided if possible.
Traditional surgical techniques employed to alleviate vertebral compression failures can involve major invasive surgical techniques with all of the possible negative consequences. Such techniques have typically required prolonged patient recuperation and unfortunately have met with limited success in alleviating pain and returning the patient to a normal life style.
More recently efforts have been made to develop surgical techniques for repair of vertebral compression failures of osteoporotic bone by using conventional instruments in a transpedicular approach to penetrate the vertebral body, including a standard syringe, and then inject a flowable synthetic bone material or bone cement directly into the vertebral body through the syringe. This technique of vertebroplasty requires that the physician take the utmost care to avoid damage to the spinal cord when drilling through the narrow dimensions of the pedicle of the vertebrae. To avoid potentially catastrophic results physicians practicing conventional vertebroplasty require the use of CAT scanning, biplane fluoroscopy, magnetic resonance imaging, or other imaging devices to ensure the proper alignment of the instruments, which bore through and are passed through the narrow pedicle. The availability of CAT scanning or sophisticated biplane fluoroscopy in surgical procedures is limited due to the additional cost associated with equipping surgical suites with the necessary equipment. Further, to protect against accidental damage to the spinal cord during the conventional transpedicular approach to the vertebral body, the patient is typically placed in a restraining device and stereotaxic procedures are used to guide the physician's drill and cannula through the pedicle. Due to the extraordinary care and precision required in conventional vertebroplasty, the time needed to complete the surgery and the cost associated with the procedure can be extensive. Further, general anesthetic is not recommended due to the close proximity of the physician's instruments to the spinal cord and the associated need to communicate with the patient. This requirement, however, also causes concern of movement of the patient during the surgery; movement which could have serious consequences should the spinal cord be damaged as a result. Scholten et al. in U.S. Pat. Nos. 4,969,888 and 5,108,404 teaches the conventional surgical technique of vertebroplasty with the additional step of employing a balloon as an expansion device within the body of the vertebrae to compact the osteoporotic cancellous bone away from the center and against the walls of the vertebral body. This additional step to conventional vertebroplasty, taught by Scholten et al., is intended to provide additional space within the vertebral body to accept the flowable bone cement through the needle (syringe). While the conventional vertebroplasty technique using conventional surgical apparatus has the distinct disadvantage of drilling through the pedicle with the potential risk of damage to the spinal column, this additional balloon expander employed in the process of Scholten et al., provides an additional disadvantage by compressing the naturally present internal matrix of the osteoporotic vertebra against the wall of the vertebral body. Absent this natural matrix, the injection of bone cement into the cavity created by the compressing step results in the formation of an unstructured bolus of bone cement in the center of the vertebral body. Because of the compression of cancellous bone, which as a result lines the walls of the vertebra, the bone cement which is infused into the vertebral body does not make a strong, direct, bonding contact with the vertebral wall, thus resulting in a potentially weaker post-surgery vertebral body.
There is, therefore, a great need for a surgical technique and associated instrumentation by which osteoporotic bone can be safely, expeditiously and efficiently treated. There is a particular need for a vertebroplasty procedure and associated instrumentation which provide a safer, faster procedure that ultimately results in a repair to the osteoporotic vertebral body wherein the injected material does not disturb the natural matrix of the cancellous bone, which along with direct contact to the vertebral wall provides a strong, composite matrix. The present invention provides an apparatus and a method of percutaneous bone failure fixation, which satisfies these needs.